Braley’s campaign sent out a fundraising letter on Thursday from Warren, the Massachusetts senator known for her anti-Wall Street rhetoric, asking supporters to donate for a chance to have lunch with her and Braley in Washington "in a few weeks."

"I know that Bruce will be the kind of senator we can count on to help me fight to level the playing field for working families across Iowa and around the country," she said in the letter.

Warren has campaigned for several other Democratic Senate candidates locked in tight races in recent months.

While Democrats ostensibly partner with Warren to burnish their image as populists, Warren herself has come under scrutiny for supporting corporations.

She recently came out in favor of reauthorization for the Export-Import Bank, a U.S. export-financing agency that Republican lawmakers have slammed as contributing to cronyism. A Warren spokesperson told the Huffington Post that she "believes that the Export-Import Bank helps create American jobs and spurs economic growth, but recognizes that there is room for improvement in the bank’s operations."

The bank helps finance the purchase of U.S. exports by foreign governments and corporations. Billions of those subsidies go to large firms such as Boeing, earning the agency the nickname of "Boeing’s Bank."

"It's shameful that someone like Elizabeth Warren, who has spent her entire career demonizing Wall Street and big corporations, is siding with them on the Export-Import Bank," Club for Growth spokesman Barney Keller told the Huffington Post. "She deserves to be held accountable just as much as the Republicans who plead fealty to the free market but support a corrupt and crony capitalist slush fund that picks winners and losers."

Additionally, critics of Warren note that she backed former industrial conglomerate LTV Steel in its 1990s fight against a congressional requirement that it pay millions of dollars into a fund for its retired coal miners’ healthcare.

Warren’s campaign said she believed that a court ruling against LTV—after it had already reorganized under bankruptcy laws in 1986—would imperil future claimants in bankruptcy cases. Ordering a company to pay up after the bankruptcy process would risk compensation for petitioners if the company shut down, she argued.

Warren’s opponents at the time said exempting LTV would encourage other companies to opt out of the healthcare fund.

Braley’s outreach to Warren comes as he continues to be portrayed as elitist by Republicans. His poll numbers dipped earlier this year after he called Sen. Chuck Grassley (R., Iowa), a popular figure in the farmer-heavy state, a "farmer from Iowa who never went to law school."

The GOP previously pounced on Braley for complaining about the lack of towel service at the taxpayer-funded House gym, badgering a health care expert about whether she had an "advanced degree," and telling a radio show host that he tries to talk to voters in "terms they can understand."

"After eight years in Washington, Bruce Braley has clearly grown more comfortable with his Capitol Hill lifestyle than our Iowa way of life," said Republican Party of Iowa Chairman Jeff Kaufmann in a statement. "Braley's tone-deaf invitation to have lunch with him and a Massachusetts liberal in D.C is further proof that he has sadly become all things Washington."

Braley’s campaign did not respond to a request for comment.

Braley and Republican Joni Ernst remain in a dead heat in the Iowa Senate race, according to the Real Clear Politics poll average. The seat could be crucial to Republicans’ efforts to retake the Senate majority this fall.

Daniel WiserEmail | Full Bio | RSSDaniel Wiser is an assistant editor of National Affairs. He graduated from UNC-Chapel Hill in May 2013, where he studied Journalism and Political Science and was the State & National Editor for The Daily Tar Heel. He hails from Waxhaw, N.C., and currently lives in Washington, D.C. His Twitter handle is @TheWiserChoice.